This clinical trial aims to study whether dual-target transcranial alternating current stimulation (tACS) applied to the auditory and motor brain region can improve repetition disorder in people with stroke, and to evaluate the safety of tACS. The main goals are to answer the following questions:

1. Can dual-tACS stimulation of the auditory and motor brain area improve repetition functions in people with aphasia after stroke?
2. Can it improve the integration of auditory information and speech motor control during communication?

Researchers will compare the effects of real tACS versus sham (placebo) stimulation to see if real stimulation leads to better outcomes in aphasia patients.

Participants will:

1. Receive one extra 20-minute session of either real or sham tACS each day for 10 days
2. Attend clinic visits before and after 10-days stimulation for clinical assessments(WAB) and fNIRS recording related brain activity

Inclusion Criteria:

• Meeting the diagnostic criteria for hemorrhagic or ischemic stroke in the Chinese Guidelines for the Prevention and Treatment of Cerebrovascular Diseases(2nd edition), with the first onset, single hemisphere stroke, and confirmed by CT or MRI,course of diease 1-6 months;
• Age ranging from 30 to 80 years old;
• Native language is Mandarin or Cantonese;
• Right-handed;
• Diagnosed with aphasia by the Western Aphasia Battery (WAB) scale;
• Able to cooperate in completing the speech repetition test;
• Normal hearing.

Exclusion Criteria:

• Currently receiving non-invasive brain stimulation treatment;
• Lesions involving the Broca or STG brain regions;
• History of epilepsy, mental illness,or other neurological or mental disorders;
• Any contraindications for transcranial electrical stimulation.